A rheumatologist is an internist or pediatrician who is qualified by additional training and experience in the diagnosis and treatment of arthritis and other diseases of the joints, muscles and bones. Many rheumatologists conduct research to determine the cause and better treatments for these disabling and sometimes fatal diseases. What kind of training do rheumatologists have? After four years of medical school and three years of training in either internal medicine or pediatrics, rheumatologists devote an additional two to three years in specialized rheumatology training. Most rheumatologists who plan to treat patients choose to become board certified. Upon completion of their training, they must pass a rigorous exam conducted by the American Board of Internal Medicine or the American Board of Pediatrics to be certified. Rheumatologists who are certified by these boards after 1990 are required to complete an extensive recertification process every ten years.